Patients seeking medical care in the United States do not consistently receive recommended care for their conditions, and mechanisms for creating successful quality improvement (QI) within health care delivery organizations are complex and poorly understood. This project is an exploratory multiple case study to describe the mechanisms, strategies, and pathways through which successful QI is generated. We will describe patterns in QI intervention (QII) teams'approaches to the fundamental tasks of a QII. Patterns will then be compared between successful and unsuccessful QIIs, between chronic and preventive care QIIs, and between QIIs in highly- and less-integrated health systems. The analysis seeks to identify and generate hypotheses relating to mechanisms, strategies, and pathways for creating success in QI. Every QII must accomplish three fundamental tasks, and every QII occurs within a specific organizational context. We have selected these four fundamental components as the dimensions of a framework we will use to organize our data collection, coding, and analysis. These dimensions are: 1) Problem Identification / Project Origination;2) Intervention Design;3) Responding to Barriers and Facilitators to implementation;and 4) Organizational Context. We will identify 40 QII cases by obtaining the cooperation of 20 of the most highly experienced, expert QII leaders in America. Each subject will then provide 2 cases-their most successful QII, and their least successful QII. This strategy intentionally maximizes the variation we will observe in terms of mechanisms and factors influencing success. Data collection will be guided by the conceptual framework. To thoroughly understand each of the case studies, we will conduct semi-structured interviews of QII leaders and other key project personnel with first-hand knowledge of the QII's history. Interview data will be supplemented both by project-related documents provided by subjects as well as by background information on the organization(s) involved with the QII. Our analytic aims are first to describe the mechanisms, strategies, and pathways to successful and unsuccessful results observed in a set of QIIs, including how health care quality improvement problems are identified, how the components of QIIs are designed, how barriers to implementation are addressed, and how organizational context influences each step. Secondly, we seek to compare the mechanisms, strategies, and pathways to successful and unsuccessful results observed in a set of QIIs between chronic and preventive domains of care and between highly integrated and less integrated health care organizations.